WORKSHEETGroup :Students name :1.2.3A. Phenomenon

Kira is chemical analyst. He would like to make Co2+ standard solution for water analysis. He dissolve some of CoCl2 crystal into volumetric flask with aquadest to make a pink solution. He take some of that solution and mix it with the water sample to get solution for analysis. He wonder that the solution turn into blue. After think loudly, he remember that Co2+will dissolve as the hydrated ion in the water, Co(H2O)62+ which is pink solution. It can make an equilibrium system with Cl- ion, based on the reaction :Co(H2O)62+ + 4Cl- CoCl42- + 6H2O (l) Pink BlueKira realize that he has a water sample that contain high concentration of chlorine so that reaction is possible happen to his solution. Kira remember that a chemical reaction that reach equilibrium state will keep its equilibrium state. Therefore, if the amount of a substance that involve in an equilibrium system is changed, the reaction would occur toward a certain direction so the reaction still in its equilibrium state. Kira want his pink solution get back. Could you help Kira to investigate the phenomenon that occur in chemical equilibrium if amount of a substance that involve in chemical equilibrium is changed so he will be able to know the way to get back his pink solution of Co(H2O)62+?

B. Problem

State a problem based on the phenomenon !

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C. Hypothesis

Make a hypothesis based on your previous problem!

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D. Data Collecting

Pay attention into the teachers demonstration and write down the important things!

K2CrO4 and K2Cr2O7 make an equilibrium system based on this reaction :2CrO42- (aq) + 2H+(aq) Cr2O72- (aq) + H2O (l) Yellow Orangea. Write down the chemicals that is used in this demonstration !............................................................................................................................................ ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

a. b. Write down the tools that is used in this demonstration !

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a. b. c. Procedures :..................................................................................................................................... ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

d. Write down your observation result in this table !Observation TableThings that observedObservation

K2CrO4 0,1 M solutionState :Color :Amount :

HCl 1 M solutionState :Color :Amount :

NaOH 1 M solutionState :Color :Amount :

Mixture of K2CrO4 0,1 M with HCl 1 MState :Color :

Mixture of K2CrO4 0,1 M with HCl 1 M + NaOH 1 MState :Color :

Answer the following question to find the answer of main problem!E. Associating

d. e. 1. What is equation of equilibrium constant and reaction quotient for the following reaction ? 2CrO42- (aq) + 2H+(aq) Cr2O72- (aq) + H2O (l)........................................................................................................................................................................................................................................................................2. What happen to that reaction quotien if concentration of H+ is increased when compared with equilibrium constant?........................................................................................................................................................................................................................................................................3. Pay attention to the equilibrium constant and reaction quotient of that reaction. What should the system do to reach back the equilibrium state if H+ ion is added?........................................................................................................................................................................................................................................................................4. Which direction is the reaction occurs more favorable to attain back the equilibrium state ?........................................................................................................................................................................................................................................................................5. Pay attention to equilibrium system of K2CrO4 and K2Cr2O7. What species that concentration is decreased when NaOH is added into the solution? ........................................................................................................................................................................................................................................................................

f. g. 6. What happen to reaction quotient of that reaction when concentration of that species is reduced if compared with equilibrium constant?........................................................................................................................................................................................................................................................................7. Pay attention to the equilibrium constant and reaction quotient. What should the system do to reach back the equilibrium state if concentration of a species in no. 5 question is decreased?........................................................................................................................................................................................................................................................................8. Which direction is the reaction occurs more favorable to attain back the equilibrium state ?........................................................................................................................................................................................................................................................................

`Is the result appropriate with your hypothesis? If it isnt appropriate, what is the different between your hypothesis with the result ?F. Testing Hypothesis

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G. Conclusion

Write down the conclusion based on the experiment that youve observed !

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